Multi-interfacial nanosheet-intercalated structure with abundant oxygen vacancies promotes electrocatalytic oxygen evolution†

The electron coupling effect at the interface and the introduction of oxygen vacancies (O_v) play critical roles in the electrocatalytic activity. The key to lowering the energy barrier of the oxygen evolution reaction (OER) is to build the interface properly and increase oxygen vacancies. In this work, a nickel phosphide on nickel foam-derived catalyst with rich O_v and a multi-interfacial nanosheet intercalated structure, labeled as (Fe,La)Ni₂P-r, was created on nickel foam by using a straightforward two-step technique, namely hydrothermal and electrochemical oxidation. The addition of Fe–La creates a heterogeneous interface on the catalyst surface, causes electron transfer and redistribution, and lowers the binding energy of intermediates. At the same time, connected with DFT, it was discovered that the addition of Fe–O_v–La significantly lowered the Gibbs free energy of the reaction process, enhanced the intermediate species adsorption, and hastened the oxygen release. Only 197 mV was required to obtain a current density of 10 mA cm⁻² with a Faraday efficiency of around 100%, and the required voltage is 390 mV at a current density of 800 mA cm⁻². This study not only presents an excellent O_v-enriched multi-interface OER electrocatalyst, but also paves a path for the development of cost-effective noble metal and polymetallic catalysts.